diff --git a/src/Illuminate/Support/Collection.php b/src/Illuminate/Support/Collection.php
index 1c54424..f7bc4e8 100644
--- a/src/Illuminate/Support/Collection.php
+++ b/src/Illuminate/Support/Collection.php
@@ -1340,7 +1340,7 @@ public function sort(callable $callback = null)
      */
     public function sortBy($callback, $options = SORT_REGULAR, $descending = false)
     {
-        $results = [];
+        list($values, $results) = [[], []];
 
         $callback = $this->valueRetriever($callback);
 
@@ -1348,16 +1348,19 @@ public function sortBy($callback, $options = SORT_REGULAR, $descending = false)
         // function which we were given. Then, we will sort the returned values and
         // and grab the corresponding values for the sorted keys from this array.
         foreach ($this->items as $key => $value) {
-            $results[$key] = $callback($value, $key);
+            $values[] = $callback($value, $key);
         }
 
-        $descending ? arsort($results, $options)
-                    : asort($results, $options);
+        $keys = array_keys($this->items);
+
+        $order = $descending ? SORT_DESC : SORT_ASC;
+
+        array_multisort($values, $order, $options, $keys, $order);
 
         // Once we have sorted all of the keys in the array, we will loop through them
         // and grab the corresponding model so we can set the underlying items list
         // to the sorted version. Then we'll just return the collection instance.
-        foreach (array_keys($results) as $key) {
+        foreach ($keys as $key) {
             $results[$key] = $this->items[$key];
         }
 
diff --git a/tests/Support/SupportCollectionTest.php b/tests/Support/SupportCollectionTest.php
index 7903bfc..8822316 100644
--- a/tests/Support/SupportCollectionTest.php
+++ b/tests/Support/SupportCollectionTest.php
@@ -795,7 +795,7 @@ public function testSortBy()
     public function testSortByString()
     {
         $data = new Collection([['name' => 'taylor'], ['name' => 'dayle']]);
-        $data = $data->sortBy('name');
+        $data = $data->sortBy('name', SORT_STRING);
 
         $this->assertEquals([['name' => 'dayle'], ['name' => 'taylor']], array_values($data->all()));
 
@@ -805,6 +805,45 @@ public function testSortByString()
         $this->assertEquals([['name' => 'dayle'], ['name' => 'taylor']], array_values($data->all()));
     }
 
+    public function testSortByMaintainsOriginalOrderOfItemsWithIdenticalValues()
+    {
+        $data = new Collection([['name' => 'taylor'], ['name' => 'dayle'], ['name' => 'dayle']]);
+
+        $data = $data->sortBy('name');
+
+        $this->assertEquals([['name' => 'dayle'], ['name' => 'dayle'], ['name' => 'taylor']], array_values($data->all()));
+        $this->assertEquals([1, 2, 0], $data->keys()->all());
+    }
+
+    public function testSortByStringMaintainsOriginalOrderOfItemsWithIdenticalValues()
+    {
+        $data = new Collection([['name' => 'taylor'], ['name' => 'dayle'], ['name' => 'dayle']]);
+
+        $data = $data->sortBy('name', SORT_STRING);
+
+        $this->assertEquals([['name' => 'dayle'], ['name' => 'dayle'], ['name' => 'taylor']], array_values($data->all()));
+        $this->assertEquals([1, 2, 0], $data->keys()->all());
+    }
+
+    public function testSortByNumericMaintainsOriginalOrderOfItemsWithIdenticalValues()
+    {
+        $data = new Collection([['name' => '2'], ['name' => '1'], ['name' => '1']]);
+        $data = $data->sortBy('name', SORT_NUMERIC);
+
+        $this->assertEquals([['name' => '1'], ['name' => '1'], ['name' => '2']], array_values($data->all()));
+        $this->assertEquals([1, 2, 0], $data->keys()->all());
+    }
+
+    public function testSortByNaturalMaintainsOriginalOrderOfItemsWithIdenticalValues()
+    {
+        $data = new Collection([['name' => 'img10.png'], ['name' => 'img1.png'], ['name' => 'img1.png']]);
+
+        $data = $data->sortBy('name', SORT_NATURAL);
+
+        $this->assertEquals([['name' => 'img1.png'], ['name' => 'img1.png'], ['name' => 'img10.png']], array_values($data->all()));
+        $this->assertEquals([1, 2, 0], $data->keys()->all());
+    }
+
     public function testSortByAlwaysReturnsAssoc()
     {
         $data = new Collection(['a' => 'taylor', 'b' => 'dayle']);